1. Field of the Invention
The present invention relates to a mask layout data creation method and a mask layout data creating apparatus with each of which mask layout data created for a particular factory facility is used to create mask layout data optimized for another factory facility, as well as a method for manufacturing a semiconductor device using the created mask layout data.
2. Description of the Prior Art
In manufacturing a semiconductor device (Large Scale Integration: LSI), circuit designing is first carried out based on a required specification. Thereafter, mask layout data is created based on the data used in the circuit designing. Subsequently, the created mask layout data is used to make a reticle. Then, the reticle is used to transfer a pattern to a semiconductor substrate, thereby a semiconductor device being manufactured. In general, software (an electronic circuit simulator) called SPICE is used in circuit design. The mask layout data is described in a format called GDS.
The circuit of a semiconductor device is usually designed by a circuit design department using its company's in-house design standard (SPICE parameter), and the semiconductor device is manufactured using the circuit design data by a manufacturing department of a company's in-house factory. However, when there is a need for an urgent increase in manufacturing of the semiconductor devices manufactured in a company's in-house factory, a problem arises that an expansion of the facility in the company's in-house factory requires not only enormous investment but also a long period of time before a semiconductor device can actually be manufactured in a newly constructed facility. Also, a problem arises that various risks are generated with the starting up of the new facility.
For this reason, in some cases, a manufacturing of semiconductor devices is outsourced (to another company). In this case, the company's in-house design standard (SPICE parameter) naturally differs from that of the other company. As a result, even when the same mask layout data (GDS data) is used to manufacture the semiconductor device, variation occurs in the characteristics of transistors which constitute semiconductor devices.
FIG. 1 shows an example of the characteristics (gate length-threshold voltage characteristics) of a transistor manufactured by an outsourcer together with an example of the characteristics of a transistor manufactured by an outsourcee (contractor) in combination. As described above, the respective companies have different design standards. Thereby, even when the same mask layout data is used, there is a difference between the characteristics of the transistors manufactured by the outsourcer and by the outsourcee. The characteristics of a transistor is related not only to a gate length but also to a junction depth of an extension layers, the thickness of a gate insulation film, the width of a side wall, the concentration of impurity in a channel layer, and the like. Accordingly, these parameters have so far been controlled so that the characteristics of the transistor manufactured by an outsourcee can become close to the characteristics of the transistor manufactured by an outsourcer.
Japanese Laid-open Patent Application Publication No. Hei 4-255266 describes an optimization of characteristics by introducing impurity into portions which serve as the channels of an intrinsic MOS transistor, a long channel MOS transistor, and a short channel MOS transistor. In addition, in a method described in Japanese Laid-open Patent Application Publication No. 2002-299611, the impurity injection conditions for a transistor having a particular gate length are decided, the concentration of impurity of the transistor is calculated, and then the concentration of impurity of a transistor having a gate length shorter than the particular gate length is calculated based on the calculation result. Thereby, the characteristics of the transistor are figured out.
As described above, in order that the characteristics of the transistor manufactured by an outsourcee will be made close to the characteristics of the transistor manufactured by an outsourcer, it is necessary to actually manufacture a transistor by controlling various parameters, to measure the characteristics of the manufactured transistors, and then to feed back the measurement results for controlling parameters. However, the above operations are so complicated that a long period of time is consumed to determine the parameters.
Moreover, when the thickness of the gate insulation film becomes thin as a result of controlling the parameters, the breakdown voltage of a transistor becomes low and this reduces the reliability of a semiconductor device. A major change in the processes and the introduction of a new manufacturing facility are further necessary to change the junction depth of the extension layer.